Scroll-Type Fluid Machine

ABSTRACT

A scroll-type fluid machine ( 1, 88 ) in which a fixed scroll ( 8 ) and a movable scroll ( 10 ), in consort, demarcate a compression or expansion chamber ( 60 ) of a lubricant-containing working fluid, the fluid machine having a housing ( 4 ) provided with a port ( 16 ) through which the working fluid passes, and a pedestal section ( 62 ) in which the port opens, and which is applied with thrust load on the back face ( 64 ) side of an end plate ( 10   a ) of the movable scroll due to the demarcation of the compression or expansion chamber. The pedestal section has a groove ( 72, 90 ) formed in a region including an opening of the port.

TECHNICAL FIELD

The invention relates to a scroll-type fluid machine suitable for a refrigeration circuit used for vehicle air conditioning.

BACKGROUND ART

A scroll-type fluid machine of this type is a scroll-type fluid machine in which a fixed scroll and a movable scroll, in consort, demarcate a compression or expansion chamber of a lubricant-containing working fluid. The fluid machine has a housing provided with a port through which the working fluid passes, and a pedestal section in which the port opens, and which is applied with thrust load on the back face side of an end plate of the movable scroll, due to the demarcation of the compression or expansion chamber.

Disclosed as one example of the scroll-type fluid machine is a scroll-type compressor in which a housing is provided with a main intake aperture leading an intake opening (intake port) into a suction chamber located in an outer periphery of both the scrolls, and with an auxiliary intake aperture, aside from the main intake aperture, which leads the intake opening to the suction chamber (see Patent Document 1, for example).

PRIOR ART DOCUMENT Patent Document

Patent Document 1 Japanese Patent No. 3227075

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

In the case of the conventional fluid machine disclosed in the Patent Document 1, the auxiliary intake aperture secures a channel of working fluid even if the opening of the main intake aperture is blocked with an end plate of the movable scroll or the like. As a result, the lubricant contained in refrigerant gas serving as working fluid reaches all parts including the back face of the movable scroll, where lubrication is needed. Lubricity of the scroll unit is thus improved.

The above-mentioned conventional technology, however, does not particularly prepare for the possibility that there occurs a local abnormal friction in a part of the back face of the movable scroll, and fails to materialize a further lubricity improvement of the scroll unit, which means that there still is an problem in materializing an effective durability improvement and a mechanical loss reduction.

The present invention provides a scroll-type fluid machine that effectively materializes the durability improvement and mechanical loss reduction of a scroll unit with a simple structure.

Means for Solving the Problems

A scroll-type fluid machine of the invention is a scroll-type fluid machine in which a fixed scroll and a movable scroll, in consort, demarcate a compression or expansion chamber of a lubricant-containing working fluid, the fluid machine having a housing provided with a port through which the working fluid passes, and a pedestal section in which the port opens, and which is applied with thrust load on the back face side of an end plate of the movable scroll due to the demarcation of the compression or expansion chamber. The pedestal section has a groove formed in a region including an opening of the port.

Preferably, the groove is formed along an inner circumferential surface of the housing.

Preferably, the groove is formed in a ring-like shape along the inner circumferential surface of the housing.

Preferably, the groove has sectional area in a radial direction of the movable scroll, which becomes smaller with increasing distance from the opening.

Preferably, the groove has a terminal portion on the opposite side of the opening as viewed in the radial direction of the movable scroll on the basis of an axis of a shaft interlocked with the movable scroll (claim 5).

Preferably, a thrust plate is provided between the pedestal section and the end plate, and the thrust plate is applied with the thrust load of the movable scroll at a sliding-contact face with which the back face comes into sliding contact (claim 6).

Preferably, the sliding-contact face of the thrust plate is increased in area with increasing distance from the opening.

Preferably, the thrust plate has such a shape as to occlude the groove with increasing distance from the opening.

Preferably, a coordinate origin of a volute of the movable scroll is positioned on the opposite side of the opening as viewed in the radial direction of the movable scroll on the basis of the axis of the shaft interlocked with the movable scroll.

Preferably, the scroll-type fluid machine of the present invention is a horizontal type in which a pivot line of the movable scroll is horizontal.

Advantageous Effects of the Invention

According to the invention, in a scroll compressor as an example of the scroll-type fluid machine, the working fluid that has passed through the intake port provided to the housing is compressed in the compression chamber demarcated by the movable and fixed scrolls. In the case of a scroll expansion machine as an example of the scroll-type fluid machine, the working fluid that has been expanded in the expansion chamber demarcated by the movable and fixed scrolls passes through a discharge port provided to the housing and then flows outside. Since the pedestal section has the groove formed in the region including the opening of the port, the working fluid passing through the opening of the port flows in the groove and reaches a wide area on the back face side of the end plate of the movable scroll. In this process, the lubricant contained in the working fluid condenses as a result of contacting a wall surface of the groove, flows out of the groove, and adheres to the pedestal section and the back face, or the working fluid itself that has flown out of the groove condenses and adheres directly to the pedestal section and the back face as a result of contacting the pedestal section and the back face. In consequence, an oil film can be formed in the wide area on the back face side of the end plate.

Especially, in the case of the scroll compressor, a refrigerant flowing in the groove is introduced little by little into the demarcated compression chamber. The refrigerant then stagnates more severely with increasing distance from the opening. This makes it difficult for the oil film to be formed in areas located away from the opening, and thus, abnormal friction is prone to take place. Nonetheless, the invention is capable of solving this problem. It is therefore possible to effectively materialize the durability improvement and mechanical loss reduction of the scroll unit with a simple structure in which the groove is merely formed in the region including the opening in the pedestal section.

According to the invention, since the groove is formed along the inner circumferential surface of the housing, the working fluid, namely, the lubricant, can be smoothly made to reach the wide area on the back face side by using the housing as a guiding member. The oil film can, therefore, be further effectively formed in the wide area on the back face side.

According to the invention, since the groove is formed in the ring-like shape along the inner circumferential surface of the housing, the working fluid can be made to reach the whole area on the back face side, and the oil film can be further effectively formed in the wide area on the back face side.

According to the invention, since the groove has the sectional area in the radial direction of the movable scroll, which becomes smaller with increasing distance from the opening, the lubricant accumulated in the groove can be proactively made to overflow in the areas located away from the opening of the groove. The oil film can, therefore, be further effectively formed in the wide area on the back face side.

According to the invention, since the groove has the terminal portion on the opposite side of the opening as viewed in the radial direction of the movable scroll on the basis of the axis of the shaft interlocked with the movable scroll, the working fluid can be made to reach the wide area on the back face side. Furthermore, a position at which the lubricant accumulated in the groove is made to overflow can be adjusted by adjusting the position of the terminal portion, so that the oil film can be further effectively formed in the wide area on the back face side.

According to the invention, the thrust plate is provided between the pedestal section and the end plate, and the thrust plate is applied with the thrust load of the movable scroll at the sliding-contact face with which the back face comes into sliding contact. In this case, the oil film can be formed in a wide area of the sliding-contact face since, in the process where the working fluid flows in the groove, the lubricant contained in the working fluid flows out of the groove and adheres to the sliding-contact face and the back face, or the working fluid itself that has flown out of the groove condenses as a result of contacting the sliding-contact face and the back face and adheres directly to the sliding-contact face and the back face.

According to the invention, since the thrust plate has the sliding-contact face that is increased in area with increasing distance from the opening, it is possible to proactively decrease the pressure, namely, surface pressure, of the working fluid, which acts upon the sliding-contact face, in the areas located away from the opening of the groove. Such a decrease in surface pressure causes the lubricant to effectively adhere to the sliding-contact face. Consequently, the oil film can be further effectively formed in the sliding-contact face.

According to the invention, since the thrust plate has such a shape as to occlude the groove with increasing distance from the opening, the lubricant can be proactively guided to the sliding-contact face without entering the groove. The oil film can, therefore, be further effectively formed.

Also, according to the invention, the coordinate origin of the volute of the movable scroll is positioned on the opposite side of the opening as viewed in the radial direction of the movable scroll on the basis of the axis of the shaft interlocked with the movable scroll. In general, the thrust load of the movable scroll fluctuates in the vicinity of the coordinate origin of the volute of the movable scroll. The fluctuating thrust load can be received at the sliding-contact face that has been reduced in surface pressure and on which the oil film is desirably formed. The scroll unit is thus further improved in durability and reduced in mechanical loss.

According to the invention, it is desirable to apply the above-described invention to a horizontal scroll-type fluid machine in which the pivot line of the movable scroll is horizontal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a scroll compressor according to a first embodiment of the invention.

FIG. 2 is a view of the inside of a front housing of the compressor shown in FIG. 1 along a line II-II in FIG. 1.

FIG. 3 is a view showing a state in which the rotation of a movable scroll shown in FIG. 2 advances by angle of 180 degrees in phase.

FIG. 4 is a view of the inside of the front housing of the compressor shown in FIG. 1 along a line IV-IV in FIG. 1.

FIG. 5 is a sectional view of a scroll compressor according to a second embodiment of the invention.

FIG. 6 is a view of the inside of a front housing of the compressor shown in FIG. 5 along a line VI-VI in FIG. 5.

FIG. 7 is a view showing a state in which the rotation of a movable scroll shown in FIG. 6 advances by angle of 180 degrees in phase.

FIG. 8 is a view of the inside of the front housing of the compressor shown in FIG. 5 along a line VIII-VIII in FIG. 5.

MODE FOR CARRYING OUT THE INVENTION

FIG. 1 shows a scroll compressor (scroll-type fluid machine) 1 according to a first embodiment of the invention. The compressor 1 is installed in a refrigeration circuit for vehicle air conditioning and used to compress a refrigerant (working fluid) circulating in the refrigeration circuit.

The compressor 1 has a rear housing 2 and a front housing (housing) 4. A scroll unit 6 is sandwiched between the rear housing 2 and the front housing 4. The scroll unit 6 is made up of a fixed scroll 8 that is fixed to the housings 2 and 4 and a movable scroll 10 that is fitted to the fixed scroll 8 in an engaged manner.

The compressor 1 is a horizontal scroll compressor in which a pivot line of the movable scroll 10 is horizontal. In response to the rotating movement of the movable scroll 10, the scroll unit 6 continuously carries out a series of processes starting with the suction of the refrigerant, then proceeding with the compression of the refrigerant, and ending with the discharge of the refrigerant.

More specifically, a discharge chamber 12 is formed in the rear housing 2 to be located between an end plate thereof and the fixed scroll 8 of the scroll unit 6. The discharge chamber 12 is connectable to a discharge aperture (not shown) formed in an end plate 8 a of the fixed scroll 8, with a reed discharge valve 14 intervening therebetween. The discharge chamber 12 is also connected to a refrigerant circulating path of the refrigeration circuit through a discharge port (not shown) formed in the rear housing 2.

An intake port (port) 16 for the refrigerant is formed in an outer circumferential wall 4 a of the front housing 4 in the form of a recess. The refrigerant introduced from the refrigerant circulating path through the intake port 16 is sucked into the scroll unit 6.

A drive shaft (shaft) 18 is disposed in the front housing 4. The drive shaft 18 has a large-diameter end 20 and a small-diameter shaft 22. The large-diameter end 20 is rotatably supported by the front housing 4 with a needle bearing 24 intervening therebetween. The small-diameter shaft 22 is rotatably supported by the front housing 4 with a ball bearing 26 intervening therebetween. A lip seal 28 is disposed between the small-diameter shaft 22 and the front housing 4. The lip seal 28 airtightly separates the inside of the front housing 4.

The small-diameter shaft 22 of the drive shaft 18 is protruding from the front housing 4. A protruding end of the small-diameter shaft 22 is interlocked with a drive pulley 30 including a built-in electromagnetic clutch. The drive pulley 30 is rotatably supported by the front housing 4 with a bearing 32 intervening therebetween. The drive pulley 30 is connected via a belt to an output pulley located on the engine side of the vehicle, and is rotated by receiving power from the engine. While the engine is being driven, therefore, the drive shaft 18 is rotated together with the drive pulley 30 if the electromagnetic clutch in the drive pulley 30 is ON.

A crankpin 34 is protruding from the large-diameter end 20 of the drive shaft 18 in the direction of the movable scroll 10. The crankpin 34 supports a boss 40 of the movable scroll 10 with an eccentric bushing 36 and the needle bearing 38 intervening therebetween. Accordingly, when the drive shaft 18 is rotated, the movable scroll 10 receives the rotation through the crankpin 34 and the eccentric bushing 36 and makes a rotating movement. A rotation preventing mechanism 42 (FIG. 2) is disposed between the front housing 4 and an end plate 10 a of the movable scroll 10.

The fixed scroll 8 has a fixed volute body 50 integrated with an end plate 8 a. The movable scroll 10 also has a movable volute body 52 integrated with the end plate 10 a. Inner and outer faces of the fixed and movable volute bodies 50 and 52, except for center end portions thereof, are formed of involute faces.

The discharge aperture is positioned close to a center end portion 54 of the fixed volute body 50. There is secured a certain clearance between the discharge aperture and an inner face of the center end portion 54. The fixed volute body 50 is provided with a fixed chip seal 56 in a tip end thereof, and the movable volute body 52 with a movable chip seal 58 in a tip end thereof. The fixed volute body 50 and the end plate 10 a are brought into sliding contact with each other with the fixed chip seal 56 intervening therebetween. The movable volute body 52 and the end plate 8 a are brought into sliding contact with each other with the movable chip seal 58 intervening therebetween. The refrigerant that has been introduced from the intake port 16 by the sliding movement between the fixed and movable scrolls 8 and 10 is sucked into the scroll unit 6. The fixed and movable scrolls 8 and 10, in consort, demarcate a compression chamber (compression or expansion chamber) 60 of a lubricant-containing refrigerant gas in the form of mist between the fixed and movable volute bodies 50 and 52. The above-mentioned series of processes is continuously conducted.

To be more specific, in the front housing 4, a pedestal section 62 is formed in an inner face of the outer circumferential wall 4 a to have a ring-like shape. The pedestal section 62 is applied with thrust load that is produced by a compression reactive force that generates along with the demarcation of the compression chamber 60, in an axial direction of the drive shaft 18, or in the direction of the pivot line of the movable scroll 10, on a back face 64 side of the end plate 10 a of the movable scroll 10. An intake aperture 68 leading to the intake port 16 opens in a pedestal face 66 of the pedestal section 62, which is located on the opposite side of the back face 64. A groove 72 is formed in a region including an opening 70 of the intake aperture 68.

The shape of the groove 72 and of a thrust plate 74 of the present embodiment, and the flow of the refrigerant gas and of the lubricant contained in the refrigerant gas will be described below in detail with reference to FIGS. 2 to 4. FIGS. 2 to 4 show the visible flows of the refrigerant gas and the lubricant with solid lines, and the flows hidden by the thrust plate with broken lines.

As is apparent from FIGS. 2 to 4, the groove 72 is formed along an inner circumferential surface 4 b of the front housing 4 in the shape of a ring whose sectional area in a radial direction of the movable scroll 10 is substantially constant. The ring-like thrust plate 74 is disposed between the pedestal section 62 and the end plate 10 a. The back face 64 comes into sliding contact with the thrust plate 74 along with the rotation of the movable scroll 10. A sliding-contact face 76 of the thrust plate 74, with which the back face 64 comes into sliding contact, functions as a thrust-receiving face onto which the thrust load of the movable scroll 10 is directly applied.

As illustrated in FIG. 4, the thrust plate 74 is formed in the shape of a ring that is uneven in a planar view, in which a convex portion 78 having a raised shape in the radial direction of the movable scroll 10 so as to occlude a part of the groove 72 to expose the rotation preventing mechanism 42 to the back face 64 side, and a concave portion 80 that is more recessed towards the rotation preventing mechanism 42 side than the groove 72 in the radial direction of the movable scroll 10, are arranged in an alternate manner.

The refrigerant gas that has been introduced from the intake port 16 passes through the intake aperture 68 and is discharged from the opening 70. The refrigerant gas then uninterruptedly flows in the groove 72 to reach a lower part of the front housing 4. In this process, the refrigerant gas is properly sucked into the scroll unit 6, and the compression chamber 60 is demarcated. At the same time, the lubricant in the form of mist, which is contained in the refrigerant gas, condenses as a result of contacting the wall surface of the groove 72, and a liquid lubricant flows down in the groove 72 together with the refrigerant gas.

When flowing down in the groove 72, a portion of the liquid lubricant flows out of the groove 72, overflowing the thrust plate 74, and adheres to the sliding-contact face 76. In result, an oil film is desirably formed in the sliding-contact face 76 even in the lower part of the front housing 4.

In the process where the refrigerant gas flows down in the groove 72, a portion of the refrigerant gas flows out of the groove 72, overflowing the thrust plate 74. The refrigerant gas itself that has overflown contacts the sliding-contact face 76 and the back face 64, and thus, the lubricant in the form of mist condenses and adheres directly to the sliding-contact face 76 and the back face 64. As a result, the oil film is desirably formed in the sliding-contact face 76.

Since the compressor 1 of the first embodiment has the groove 72 as described above, the refrigerant gas that has been guided from the intake port 16 is discharged from the opening 70, flows in the groove 72, and reaches the wide area of the sliding-contact face 76. In this process, the lubricant contained in the refrigerant gas condenses as a result of contacting the wall surface of the groove 72, flows out of the groove 72, and adheres to the sliding-contact face 76 and the back face 64, or the refrigerant gas itself that have flown out of the groove 72 contacts the sliding-contact face 76 and the back face 64 to condense and adhere directly to the sliding-contact face 76 and the back face 64. The oil film can, therefore, be formed in the wide area of the sliding-contact face 76.

As a consequence, the refrigerant gas flowing in the groove 72 is introduced little by little into the demarcated compression chamber 60, and the refrigerant then stagnates more severely with increasing distance from the opening 70. The oil film of the sliding-contact face 76 therefore becomes difficult to be formed especially in the lower part of the front housing. This makes it easy for abnormal friction to take place. Nonetheless, the invention is capable of solving this problem. It is therefore possible to effectively materialize the durability improvement and mechanical loss reduction of the scroll unit 6 with a simple structure in which the groove 72 is merely formed in the region including the opening 70 of the pedestal section 62.

Since the groove 72 is formed along the inner circumferential surface 4 b of the front housing 4, the refrigerant, namely lubricant, can be smoothly made to reach the wide area of the sliding-contact face 76 by using the front housing 4 as a guiding member. Furthermore, since the groove 72 is formed in the ring-like shape along the inner circumferential surface 4 b of the front housing 4, the refrigerant can reach the whole area of the sliding-contact face 76, and the oil film can be effectively formed in the sliding-contact face 76 in the lower part of the front housing 4.

FIG. 5 shows a scroll compressor (scroll-type fluid machine) 88 according to a second embodiment of the present invention. Constituents identical to those of the compressor 1 of the first embodiment will be provided with the same reference numerals, and the description thereof will be omitted, or the reference numerals will be omitted.

The shape of the groove 90 and of a thrust plate 92 of the present embodiment and the flow of the refrigerant gas and of the lubricant contained in the refrigerant gas will be descried below with reference to FIGS. 6 to 8. FIGS. 6 to 8 show the visible flows of the refrigerant gas and the lubricant with solid lines, and the flows hidden by the thrust plate with broken lines.

As is apparent from FIGS. 6 to 8, the groove 90 is formed along an inner circumferential surface 4 b of the front housing 4 in the shape of a ring whose sectional area in the radial direction of the movable scroll 10 becomes smaller with increasing distance from the opening 70. The thrust plate 92 has an enlarged sliding-contact portion 96, a sliding-contact face 94 of which is increased in area with increasing distance from the opening 70. The enlarged sliding-contact portion 96 occludes the groove 90 in the lower part of the front housing 4.

As illustrated in FIG. 8, the coordinate origin O of the volute of the movable scroll 10 is positioned on the opposite side of the opening 70 in the radial direction of the movable scroll 10 on the basis of an axis C of the drive shaft 18 interlocked with the movable scroll 10, that is, on the enlarged sliding-contact portion 90 side.

As mentioned above, in the compressor 88 of the second embodiment, since the sectional area of the groove 90 is reduced with increasing distance from the opening 70, the lubricant that has been accumulated in the groove 90 can be proactively made to overflow in areas located away from the opening 70 of the groove 90, that is, in the lower part of the front housing 4, and is guided to the sliding-contact face 94 as illustrated in FIG. 8. The oil film can, therefore, be further effectively formed in the sliding-contact face 94 in the lower part of the front housing 4.

Moreover, the enlarged sliding-contact portion 96 makes it possible to proactively reduce the pressure of the refrigerant acting upon the sliding-contact face 94, that is, the surface pressure of the sliding-contact fact 94, in the lower part of the front housing 4. Due to the decrease of the surface pressure, the lubricant can be effectively made to adhere to the sliding-contact face 94 of the enlarged sliding-contact portion 96. The oil film can, therefore, be further effectively formed in the sliding-contact face 94 in the lower part of the front housing 4.

Since the enlarged sliding-contact portion 96 has such a shape as to occlude the groove 90, the lubricant can be proactively guided to the sliding-contact face 94 of the enlarged sliding-contact portion 96 without entering the groove 90. This makes it possible to further effectively form the oil film in the sliding-contact face in the lower part of the front housing 4.

Also, the coordinate origin O of the volute of the movable scroll 10 is positioned on the enlarged sliding-contact portion 96 side. In general, the thrust load of the movable scroll 10 fluctuates in the vicinity of the coordinate origin O of the volute of the movable scroll 10. As a result, the fluctuating thrust load can be received at the sliding-contact face 94 of the enlarged sliding-contact portion 96, which has been reduced in surface pressure and in which the oil film is desirably formed. The scroll unit 6 is thus further improved in durability and reduced in mechanical loss.

The invention is not limited to the above-described embodiments, and may be modified in various ways. For example, the grooves 72 and 90 of the invention do not necessarily have to be formed in a ring-like shape. The grooves 72 and 90 may be formed in the shape of letter Ω by forming a terminal portion (not shown) on the opposite side of the opening 70 in the radial direction of the movable scroll 10 on the basis of the axis C of the drive shaft 18. Again, the refrigerant can be made to reach the wide area of the sliding-contact faces 76 and 94. Moreover, the position, at which the lubricant accumulated in the grooves 72 and 90 is made to overflow, can be adjusted by adjusting the position of the terminal portion, so that the oil film can be further effectively formed in the sliding-contact faces 76 and 94 in the lower part of the front housing 4.

The shape of the thrust plates 74 and 92 of the invention is not limited to the one illustrated in the drawings as long as the convex portion 78 and the concave portion 80 or the enlarged sliding-contact portion 96 are properly formed.

The compressor of the invention is not always required to have the thrust plates 74 and 92. On the condition that at least the grooves 72 and 90 are provided, the same advantages can be provided by the compressor having a structure in which the pedestal face 66 of the pedestal section 62 comes into sliding contact with the back face 64.

Needless to say, the invention may be applied not only to the horizontal scroll compressor but also to a vertical scroll compressor, and may also be applied to all scroll-type fluid machines, including a scroll expansion machine in which an expansion chamber of refrigerant is demarcated.

EXPLANATION OF REFERENCE SIGNS

-   1, 88 scroll compressor (scroll-type fluid machine) -   4 housing -   4 b inner circumferential face -   8 fixed scroll -   10 movable scroll -   10 a end plate -   16 intake port (port) -   18 drive shaft (shaft) -   60 compression chamber (compression or expansion chamber) -   62 pedestal section -   64 back face -   72, 90 groove -   74, 92 thrust plate -   76, 94 sliding-contact face 

1. A scroll-type fluid machine in which a fixed scroll and a movable scroll, in consort, demarcate a compression or expansion chamber of a lubricant-containing working fluid, the fluid machine comprising: a housing provided with a port through which the working fluid passes, and a pedestal section in which the port opens, and which is applied with thrust load on the back face side of an end plate of the movable scroll due to the demarcation of the compression or expansion chamber, characterized in that: the pedestal section has a groove formed in a region including an opening of the port.
 2. The scroll-type fluid machine according to claim 1, characterized in that the groove is formed along an inner circumferential surface of the housing.
 3. The scroll-type fluid machine according to claim 1, characterized in that the groove is formed in a ring-like shape along the inner circumferential surface of the housing.
 4. The scroll-type fluid machine according to claim 1, characterized in that the groove has sectional area in a radial direction of the movable scroll, which becomes smaller with increasing distance from the opening.
 5. The scroll-type fluid machine according to claim 1, characterized in that the groove has a terminal portion on the opposite side of the opening as viewed in the radial direction of the movable scroll on the basis of an axis of a shaft interlocked with the movable scroll.
 6. The scroll-type fluid machine according to claim 1, characterized in that a thrust plate is provided between the pedestal section and the end plate, and the thrust plate is applied with the thrust load of the movable scroll at a sliding-contact face with which the back face comes into sliding contact.
 7. The scroll-type fluid machine according to claim 6, characterized in that the sliding-contact face of the thrust plate is increased in area with increasing distance from the opening.
 8. The scroll-type fluid machine according to claim 6, characterized in that the thrust plate has such a shape as to occlude the groove with increasing distance from the opening.
 9. The scroll-type fluid machine according to claim 7, characterized in that a coordinate origin of a volute of the movable scroll is positioned on the opposite side of the opening as viewed in the radial direction of the movable scroll on the basis of the axis of the shaft interlocked with the movable scroll.
 10. The scroll-type fluid machine according to claim 1, characterized by being a horizontal type in which a pivot line of the movable scroll is horizontal. 